1. Field of the Invention
The present invention relates to a printing system to which an image forming apparatus, an information processing apparatus, and a management server are connected via a network. More specifically, the present invention relates to a printing system that embeds copy restriction information for controlling the copying of a printed document, a print restriction method for the printing system, a program, and a storage medium.
2. Description of the Related Art
Recently, as more IT systems and apparatuses are introduced into offices, interest in security is growing. For example, there often occurs an incident of leakage of customer information which a company has. This means that privacy of individuals is threatened, which raises a serious social problem.
To cope with such problems, countermeasures are taken by setting access rights for access to electronic confidential information and setting up a device for surveillance in firewall, in order to prevent leakage of information to the outside of an office. The other countermeasures include inhibition of bringing in or out notebook computers and transportable media, such as USB memories.
In the case of the electronic confidential information, by deciding and implementing a policy on the above-mentioned surveillance, it is possible to provide protection on the information. However, when the confidential information is printed on a sheet medium by a printing apparatus, it is difficult to check the bringing of the sheet medium having the confidential information printed thereon out of an office, and inhibit the medium from being carried out of the office. The maintenance of security is more difficult in this case than in the case of restricting the electronic confidential information from being brought out of the office.
In view of these circumstances, there has been proposed a technique of embedding control information in a document when printing the same, for controlling e.g. permission or inhibition of copying of the printed document under specified conditions, to thereby secure security for copying thereof. Specifically, there has been disclosed a technique of embedding the above-mentioned control information in the form of a dot pattern or a barcode in an original to thereby restrict copying of the original (see e.g. Japanese Patent Laid-Open Publication No. 2003-280469).
In this technique, control information describing restriction of a copying operation is embedded as an image pattern in a printed document, and is read when reading an image of the printed document. Based on the read information, complicated control such as inhibition of copying or permission of copying under specified conditions is determined, whereby it is possible to automatically control the copying operation, saving user's time and effort.
On the other hand, in a printer (image forming apparatus) commonly used by a plurality of computers, with a view to improving printing processing efficiency or attaining effective use of consumables, various kinds of restriction are provided on the functions of printing processing of the printer which are permitted to be used by users.
For example, in a printer which places a restriction on the permission of color printing on a user basis, when a request for an operation of color printing is received, printing is performed after automatically changing the printing condition of color printing into monochrome printing (see e.g. Japanese Patent Laid-Open Publication No. 2002-103753)
For a printer which forcibly performs scaled-down printing on a user basis, there has been proposed a technique of reducing data for two pages to data for one page and printing the reduced data. Further, when double-sided printing is forced, even when a request for single-sided printing is made, the printer automatically executes double-sided printing.
A technique is also proposed in which such optimization of printing is performed not only after the printer automatically changes the settings of printing but also after once displaying a print changing function for the user when changing the printing conditions (see e.g. Japanese Patent Laid-Open Publication No. 2004-220532).
However, the above-mentioned conventional techniques suffer from the following problems: As described in Japanese Patent Laid-Open Publication No. 2003-280469, when performing printing by embedding copy restriction information by a barcode or dot pattern, a change in the printing conditions having effects on a user basis also affects embedded information, which makes it impossible to properly embed the information.
For example, as described in Japanese Patent Laid-Open Publication No. 2002-103753, the printer changes the printing condition of color printing to monochrome printing. Even when desired to add copy restriction information in the form of a yellow dot pattern so as to make the information unobtrusive, the function of monochrome printing acts to make it impossible to embed the print restriction information in an unobtrusive manner. Further, when a forced change to double-sided printing is made, an image embedded on the reverse side of a sheet appears on an image embedded on the front side, for example, depending on the type of the sheet, which makes it impossible to properly read the embedded information. Further, when printing is executed by forcedly reducing the size of image data, the embedded image is also reduced in size, which can result in breakage of the embedded information.